Seoul said Thursday that three people have been infected by Middle East Respiratory Syndrome (MERS) and 64 people, including health care workers and the patients’ families, are being monitored for possible infection.

All three patients were quarantined at a government-certified facility and reported to be in stable condition.

The first confirmed patient was diagnosed with the disease on Wednesday, about 17 days after he returned to Korea from trip to the Middle East and eight days after he started showing symptoms, including high fever and coughing.

Health authorities said Thursday the patient spent time in the United Arab Emirates and Saudi Arabia, in addition to Bahrain ― which he initially claimed was the only country he visited ― during his trip that lasted from April 18 to May 3.

More than 95 percent of the confirmed patients worldwide lived in the Middle East, particularly Saudi Arabia and the UAE. To date, there are no confirmed cases of MERS in Bahrain.

The second confirmed patient is his 63-year-old wife and the third is a 76-year-old who had shared the hospital room with him prior to his diagnosis. The first and third patients reportedly only stayed in the same room for five hours. Before being quarantined at the government facility on Wednesday, the first patient had visited four different medical clinics and hospitals in the course of nine days, from May 11 to 20. During this period, he had already been showing symptoms.

The 64 individuals to be quarantined at home and monitored by authorities include health care workers in the 4 medical institutions, as well as the patients’ close family members and friends. The authorities, however, did not include other patients who were present when the confirmed patient stayed at the four medical clinics and hospitals in their monitoring list.

“The virus does not appear to spread easily among people in public settings,” said Kim Woo-joo, the head of the Transgovernmental Enterprises for Pandemic Influenza in Korea.

According to Dr. Shin Hyoung-shik, who is currently treating the confirmed patients, all the three are in stable condition. The first patient had been experiencing shortness of breath, along with fever and coughing, but his condition has improved since Wednesday, he said. His wife and the third patient currently only have a fever.

MERS is known to be caused by coronaviruses, a large family of viruses that causes a range of illnesses in humans from the common cold to Severe Acute Respiratory Syndrome. There is no known cure or vaccine for MERS.

More than 95 percent of the confirmed cases worldwide were in the Middle East, particularly Saudi Arabia and the UAE.

Since it was first identified in 2012 in Saudi Arabia, 1,142 people from 23 countries have been infected by the virus. Among them, 465 died from the disease.